Transport layer

Transport layer

1. TCP & UDP

   • TCP communication process
     • TCP server processes
       • Each application process that runs on the server is configured to use a port number
         • Hosts keep track of each data segment within a session
       • TCP is a full duplex protocol
   • Reliability and flow control
     • The TCP segments can reach their destination untidy.
     • The sequence number represents the first data byte of the TCP segment.
     • The TCP receiver process places the segment data in a receive buffer
   • UDP communication
     • UDP is a simple protocol that provides the basic functions of the transport layer
       • The low UDP overhead is very desirable for simple request and response transaction protocols.
         • When UDP datagrams are sent to a destination, they often take different routes and arrive in the wrong order
           • UDP-based applications are assigned known or registered port numbers
   • TCP and UDP
     • Applications that use TCP
       • HTTP
       • FTP
       • SMTP
       • TELNET
     • Applications that use UDP
       • Multimedia applications and live video
       • Applications with simple requests and answers
       • Applications that handle reliability on their own

2. Transport Layer Protocols

   • Data transport
     • Transport layer function
       • It is responsible for establishing a temporary communication session between two applications
     • Responsibilities of the transport layer
       • Tracing
         • Track an individual conversation between an application
       • Segmentation
         • Divide the data into segments for better transport
       • Application ID
         • It guarantees that the applications receive the correct data
     • The transport layer is also responsible for managing the reliability requirements of conversations.
       • TCP is considered a reliable and complete transport layer protocol
     • The segments must arrive in a very specific sequence
       • Applications that transmit stored audio and video use TCP
   • General description
     • TCP features
       • Session establishment
         • It guarantees that the application is ready to receive data
       • Reliable delivery
         • Apply the lost segment forwarding to receive them completely
       • Delivery in the same order
         • It guarantees that the segments are in the correct order
       • Flow control
         • It guarantees that the receiver receives the data
     • TCP header
       • Source port (16 bits) and destination port (16 bits)
       • Sequence number (32 bits)
       • Recognition Number (32 bits)
     • UDP Features
       • UDP is a lightweight transport protocol
       • The data is destroyed in the order received
       • Lost segments are not resubmitted
       • No session establishment
     • UDP header
       • UDP is a protocol without status information
       • To transmit live video and voice over the network is that the data flow quickly